Heat pumps



P. B. MOORE Sept. 29, 1964 HEAT P UuPs United States Patent O 3,150,501 HEAT PUMPS Paul B. Moore, Staunton, Va., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Apr. 8, 1963, Ser. No. 271,086 3 Claims. (Cl. @L -174) This invention relates to reverse cycle refrigeration systems known as heat pumps, and used to cool and heat indoor air.

A heat pump used for conditioning indoor air in both summer and winter, consists of `an indoor air coil, `an outdoor air coil, a refrigerant compressor, a two-Way expansion means which usually is a capillary tube, and a refrigerant reversal valve. It is Well known that the xrefrigerant charge in such a heat pump is selected for air cooling operation, and that this charge is, larger than can be evaporated by the outdoor air coil during air heating operation, resulting in liquid overflowing the liquid receiver and lowing into the compressor.

The G. L. Biehn Patent No. 2,785,540 discloses how a refrigerant charge and a capillary tube expansion means can be selected for air cooling operation; how an additional constriction can automatically be added in series with the capillary tube when the heat pump is switched from air cooling to air heating operation for reducing the refrigerant supplied to the outdoor air coil, and how an auxiliary heat exchange coil can be placed in series with the indoor air coil for storing the excess refrigerant during air heating operation, the auxiliary coil and the indoor air coil having common, plate type, extended surface ns.

This invention is an improvement over that of the Biehn patent in that instead of using a finned coil forming a part of the indoor air coil for storing the excess refrigerant during air heating operation, it uses a bare, serpentine coil in each refrigerant circuit between a constriction increasing' valve and the finned indoor air coil for storing the excess refrigerant backed up!l by such valve. Such a storage coil being bare, dissipntes little heat, and therefore, performs no condenser function. It adds very little capacity during air cooling operation so that the initial balance is practically unaffected. By initial balance is meant the balance between the volume of the indoor air coil and that of the outdoor air coil for proper air cooling operation. In addition, the bare coil offers negligible air resistance. Since the bare coil is unloaded from an air standpoint, the liquid which is condensed -in the indoor air coil during air heating operation is induced to leave the latter for the storage area of the bare coil where it awaits admittance to its associated capillary tube as required. Since the storage coil forms no part of the indoor air coil, the latter can be much smaller than is used in the heat pump of the Biehn patent.

An object of this invention is to provide a heat pump that will be self balancing during both air cooling and air heating operation.

This invention will now be described with reference to the annexed drawings, of which:

FIG. 1 is a diagrammatic View of a heat pump embodying this invention, and FIG. 2 is an enlarged side section of one of the control valves of FIG. l.

An indoor air coil has horizontally spaced-apart rows 11, 12 and 13 of vertically spaced-apart tubes having common tins 9. The top Itubes are connected to a header 14 that is connected by a tube 15 to a refrigerant reversal valve 16 having a reversing arm 17. The valve 16 is connected by a tube 20 to the discharge side of hermetic compressor 21, the suction side of which is connected by tube 22 to the outlet of suction line accumulator 23, the inlet of which is connected by tube 24 to the Valve 16.

' Patented Sept. 29, 1964 The valve 16 is also connected by tube 26 to header 27 of outdoor air coil 28. The coil 28 has horizontally spacedapart rows 30, 31, and 32 of vertically spaced-apart tubes having common fins 33. The bottom tube of the row 30 of the coil 28 is connected by tube 35, filter 36, capillary tube 37, control valve 38, bare tube 39, bare serpentine coil 40 and bare tube 41 to the bottom tube of the row 11 of tubes of the indoor air coil 10. The bottom tube of the row 31 of tubes of the coil 28 is connected by tube 42, filter 43, capillary tube 44, control valve 45, bare tube 46, bare serpentine coil 48 and bare tube 49 to the bottom tube of the row 12 of -tubes of the coil 10. The bottom tube of the row 32 of tubes of the coil 28 is connected by tube 50, lter 51, capillary tube 52, control valve 53, bare tube 54, bare serpentine coil 55 and bare tube 56 to the bottom tube of the row 13 of tubes of the coil 10.

A control valve 38 is shown by FIG. 2, and corresponds to the valve shown by FIG. 2 of the Biehn patent. The control valves 45 and 53 me similar. The capillary tube 37 connects with one end of chamber 60 within the valve 38. The tube 39 connects with the other end of the chamber 60. A partition 61 extends vertically across the chamber 60 at about its center, and has therein an upper opening 62 and a larger, lower opening 63. A ball 64 is Within the chamber 60 opposite the opening 63 and between it and the end of the chamber 60 with which the tube 39 connects. A pin 65 extends vertically within the chamber 60 between the ball 64 and the end of the chamber with which the tube 39 connects. During air heating operation, the flow of refrigerant is in the direction shown by the solid arrows, and the ball 64 is moved by the flowing refrigerant to close the opening 63 as shown by FIG. 2. This causes the refrigerant to flow through the small opening 62 only. During air cooling operation, the refrigerant flow is in the opposite direction shown by the dashed-line arrows, and the ball is moved by the flowing refrigerant away from against the large opening 63, causing the refrigerant to flow through both openings 62 and 63.

The lengths of and the internal diameters of the capillary tubes, and the refrigerant charge are selected to provide proper operation during air cooling operation. The control valves add sufficient resistance to the ow of the refrigerant during air heating operation to reduce the volume of refrigerant supplied to the outdoor coil 28 to that required for proper air heating operation.

The tubes 39, 46, 54, 41, 49 and 56, and the tubes from which the coils 40, 48 and 55 are formed are similar; are bare, and have much larger inner diameter Ithan do the capillary tubes so that they offer negligible resistance to the flow of refrigerant.

Preferably, the coils 40, 48 and 55 are stacked one above the other at the downstream side with respect to air flow of the coil 10 and are spaced from the latter so as to be out of contact therewith. In these locations they can perform no condensing function during air heating operation. The heat in the air to which they are exposed is insufficient to form gas within them.

Air Cooling Operation In air cooling operation, lthe reversal valve 16 is adjusted to cause refrigerant gas from the compressor 21 to flow throhgh the tube 26 and header 27 into the rows 30, 31 and 32 of tubes of the outdoor coil 28 acting as a condenser, then from the bottom tubes of the coil 28 and through the filters 36, 43 and 51, the capillary tubes 37, 44 and 52 respectively, the control valves 38, 45 and 53 respectively, the tubes 39, 46 and 54 respectively, the serpentine coils 40, 48 and 55 respectively, and the tubes 41, 49 and 56 respectively, into the bottom tubes of the rows 11, 12 and 13 respectively, of the indoor air coil 10 which operates as an evaporator. The refrigerant flows U from the top tubes of the coil 16 through the header 14, tube 15, reversal valve 16, tube 24, accumulator 23 and tube 22 to the suction side of the compressor 21.

The flow of refrigerant through the control valves 38, 4-5 and 53 moves the check balls of the latter from against the lower openings in their partitions so that the control valves offer no significant resistance to refrigerant fiow.

The refrigerant is evaporated within the tubes of the indoor air coil. The tubes 39, 46 and 54, the serpentine coils 40, 48 and 5S, and the tubes 41, 49 and S6 contain flash gas and refrigerant. Due to the tubes 39, 46 and 54, the coils 40, 48 and 55, and the tubes 41, 49 and 56 being bare, they cause no significant pressure drop so that the initial balance is practically unaffected, and they stabilize suction gas superheat by improving the quality of the liquid made available to the indoor air coil.

Air Healing Operation In air heating operation, the reversal valve 16 is adjusted to route refrigerant gas from the compressor 21 through the tube 1S and header 14 into the rows 11, 12 and 13 of the tubes of the indoor air coil 10 operating as a condenser. The refrigerant fiows from the bottom tubes of the coil 10, the tubes 41, 49 and 56, the serpentine coils 4?, 48 land 55 respectively, the tubes 39, 46 and 54 respectively, the control valve 3S, 45 and 53 respectively, the capillary tubes 37, 44 and 52 respectively, the filters 36, 43 and 51 respectively, and the tubes 35, 42 and 50 respectively, into the bottom tubes of the rows 30, 31 and 32 respectively, of the outdoor air coil 28 operating as an evaporator. The refrigerant flows from the top tubes of the coil 2S through the header 27 and tube 26, reversal valve 16, accumulator 23 and tube 22 to the suction side of the compressor 21.

The fiow of refrigerant through the control valves 38, 45 and 53 moves their check balls against the lower openings in their partitions, closing such lower openings, and adding sufficient resistance to the refrigerant fiow to reduce the charge to that proper for air heating operation. The control valves back up the excess refrigerant, causing it to be stored within the bare tubes 39, 46 and 54, the serpentine coils 40, 48 and 55 and the bare tubes 41, 49 and 56. Since these tubes and coils are bare, they perform no condenser function and so are free to receive and store the excess liquid from the coil 10. Head pressures are reduced, providing a more dependable reserve of liquid to Work against the ball checks in the control valves, and improving the quality of Ithe liquid that the ball checks permit to enter the capillary tubes, thus raising `the back pressure within the outdoor air coil.l

In both cooling and heating operation, the suction line accumulator acts to store un-needed refrigerant as it ceases to be required by changing ambient temperatures.

In both air cooling and heating operation, the bare serpentine coils offer little resistance to air flow.

What is claimed is:

l. A heat pump comprising a finned, indoor air coil, a finned, outdoor air coil and a capillary tube connected in a closed refrigerant circuit, with said tube forming a twoway means for expanding refrigerant from each of said coils into the other of said coils, a refrigerant reversal valve in said circuit for directing refrigerant to flow from said outdoor coil operating as a condenser through said tube into said indoor coil operating as an evaporator for air cooling, or from said indoor coil operating as a condenser for air heating through said tube into said outdoor coil operating as an evaporator, the length and internal diameter of said tube being selected and said circuit containing a charge of refrigerant selected for proper air cooling operation, a control valve connected in said circuit between said tube and said indoor coil and containing means operated by refrigerant flow when the flow is from said indoor coil through said control valve and said tube to said outdoor coil for adding resistance to refrigerant flow, and operated by refrigerant tiow when the fiow is from said outdoor coil through said tube and control valve to said indoor coil for removing said resistance, and bare tubing having a portion formed as a coil connected in said circuit to said control valve and to said indoor coil, said bare tubing having an internal diameter substantially larger than that of said tube so that it offers negligible resistance to refrigerant flow, and having dimensions sufcient to store the excess refrigerant backed up by said control valve when the refrigerant liow is from said indoor coil through said control valve and capillary tube to said outdoor coil.

2. A heat pump as claimed in claim l in which said coil formed from said bare tubing is a serpentine coil, in which said indoor coil has a downstream side with respect to air flow, and in which said serpentine coil is downstream of and spaced from said downstream side of said indoor coil.

3. A heat pump as claimed in claim 2 in which said serpentine coil has substantially parallel turns laced back and forth opposite said downstream side of said indoor coil.

References Cited in the file of this patent UNITED STATES PATENTS 2,785,540 Biehn Mar. 19, 1957 

1. A HEAT PUMP COMPRISING A FINNED, INDOOR AIR COIL, A FINNED, OUTDOOR AIR COIL AND A CAPILLARY TUBE CONNECTED IN A CLOSED REFRIGERANT CIRCUIT, WITH SAID TUBE FORMING A TWOWAY MEANS FOR EXPANDING REFRIGERANT FROM EACH OF SAID COILS INTO THE OTHER OF SAID COILS, A REFRIGERANT REVERSAL VALVE IN SAID CIRCUIT FOR DIRECTING REFRIGERANT TO FLOW FROM SAID OUTDOOR COIL OPERATING AS A CONDENSER THROUGH SAID TUBE INTO SAID INDOOR COIL OPERATING AS AN EVAPORATOR FOR AIR COOLING, OR FROM SAID INDOOR COIL OPERATING AS A CONDENSER FOR AIR HEATING THROUGH SAID TUBE INTO SAID OUTDOOR COIL OPERATING AS AN EVAPORATOR, THE LENGTH AND INTERNAL DIAMETER OF SAID TUBE BEING SELECTED AND SAID CIRCUIT CONTAINING A CHARGE OF REFRIGERANT SELECTED FOR PROPER AIR COOLING OPERATION, A CONTROL VALVE CONNECTED IN SAID CIRCUIT BETWEEN SAID TUBE AND SAID INDOOR COIL AND CONTAINING MEANS OPERATED BY REFRIGERANT FLOW WHEN THE FLOW IS FROM SAID INDOOR COIL THROUGH SAID CONTROL VALVE AND SAID TUBE TO SAID OUTDOOR COIL FOR ADDING RESISTANCE TO REFRIGERANT FLOW, AND OPERATED BY REFRIGERANT FLOW WHEN THE FLOW IS FROM SAID OUTDOOR COIL THROUGH SAID TUBE AND CONTROL VALVE TO SAID INDOOR COIL FOR REMOVING SAID RESISTANCE, AND BARE TUBING HAVING A PORTION FORMED AS A COIL CONNECTED IN SAID CIRCUIT TO SAID CONTROL VALVE AND TO SAID INDOOR COIL, SAID BARE TUBING HAVING AN INTERNAL DIAMETER SUBSTANTIALLY LARGER THAN THAT OF SAID TUBE SO THAT IT OFFERS NEGLIGIBLE RESISTANCE TO REFRIGERANT FLOW, AND HAVING DIMENSIONS SUFFICIENT TO STORE THE EXCESS REFRIGERANT BACKED UP BY SAID CONTROL VALVE WHEN THE REFRIGERANT FLOW IS FROM SAID INDOOR COIL THROUGH SAID CONTROL VALVE AND CAPILLARY TUBE TO SAID OUTDOOR COIL. 